Effects of ethanol on fetal fuels and brain growth in rats.

The mechanism of fetal brain growth retardation caused by maternal alcoholism is unclear. In this study we examined fuel concentrations in brain and blood samples and their relationship to brain growth in term fetuses of rats fed ethanol during pregnancy. The offspring of ethanol-fed (EF) rats showed a significant decrease in body and brain weights compared with those of pair-fed (PF) control rats and control rats given free access to food (ad libitum fed) (AF). The EF and PF rats consumed nearly 20% less food than the AF rats, and both groups showed a slight but significant reduction of the maternal blood glucose level. In PF rats, beta-hydroxybutyrate concentration was increased in maternal as well as in fetal blood and brain samples, but no adverse effect of this magnitude of maternal undernutrition was observed on fetal body or brain weights. In EF fetuses, plasma glucose and pyruvate levels were decreased and lactate levels were increased, resulting in a nearly twofold increase in the lactate-to-pyruvate ratio when compared with levels in control fetuses. The beta-hydroxybutyrate--to-acetoacetate ratio was increased because of low plasma acetoacetate concentration. In EF fetuses, brain glucose and pyruvate levels were decreased. Fetal brain weight showed a positive correlation with brain glucose concentration and a negative correlation with the brain concentrations of lactate or ketones. It is surmised that an aberrant fetal fuel mixture may play a role in the fetal growth retardation associated with maternal alcoholism.