Dietary Soy Preserves Cognitive Function in Experimental Fetal Alcohol Spectrum Disorder: Role of Increased Signaling through Notch and Gonadotropin Releasing Hormone Networks.

Background: Neurodevelopmental abnormalities in experimental fetal alcohol spectrum disorder (FASD) are associated with impaired signaling through complex pathways that mediate neuronal survival, growth, migration, energy metabolism, and plasticity. Gestational dietary soy prevents alcohol-related impairments in placentation and FASD-associated fetal anomalies.

Objective: This study was designed to determine if gestational dietary soy would be sufficient to normalize cognitive function in young adolescent offspring after chronic in utero exposure to alcohol. In addition, efforts were made to characterize the mechanisms of FASD prevention by maternal dietary soy.

Methods: Pregnant Long Evans rats were fed isocaloric liquid diets containing 0% or 26% caloric ethanol with casein or soy isolate as the protein source from gestation day 6 through delivery/postnatal day 0 (P0). From P24 - P28, the offspring were subjected to Morris water maze (MWM) testing, and on P35, they were sacrificed to harvest temporal lobes for histopathologic and molecular studies.

Results: The in-utero ethanol-exposed offspring exhibited significant performance impairments on the MWM test, and they had a significantly reduced mean brain weight with neuronal loss in the CA1 hippocampal region and evidence of white matter myelin loss. Gestational dietary soy nearly normalized MWM performance and preserved brain weight, hippocampal CA1 architecture, and white matter myelin staining in alcohol-exposed offspring. Mechanistically, the main positive effects of soy included increased temporal lobe expression of HES-1 and HIF-1α, reflecting enhanced Notch signaling, and broadly increased expression of GnRH network molecules, including Erb1, Gper1, GnRH, GnRH-R, KiSS, and KiSS-R, irrespective of gestational ethanol exposure.

Conclusions: Dietary soy intervention early in pregnancy may reduce FASD-associated cognitive deficits. The findings suggest that targeting Notch and GnRH-related networks may help reduce long-term disability with FASD. Additional mechanistic and experimental research is needed to determine if longer-duration, postnatal dietary soy could prevent the adverse neurobehavioral effects of FASD.