Ethanol and fetal nutrition: effect of chronic ethanol exposure on rat placental growth and membrane-associated folic acid receptor binding activity.

Rat placental composition and specific folate receptor activity were measured at 20 days gestation in dams exposed to chronic high doses of ethanol (6%, vol/vol) throughout gestation and in isocalorically pair-fed controls. Ethanol-exposed fetuses were smaller (ethanol = 3.28 +/- 0.08 vs. control = 4.01 +/- 0.10 g, p less than 0.001), but their placentae were larger (experimental = 0.534 +/- 0.02 vs. control = 0.399 +/- 0.01 g, p less than 0.001). The increased weight appears to be secondary to hyperplasia as total DNA was increased while the wet/dry, RNA/DNA, and protein/DNA ratios were not different. Despite larger placentae, specific folate receptor activity was significantly reduced in the ethanol-exposed tissue, whether expressed relative to membrane protein, placental weight, or total placental binding. These results confirm that ethanol exposure is placentotoxic and suggest an additional mechanism by which ethanol may lead to intrauterine growth retardation; namely, decreased folate receptor activity.