Prenatal alcohol exposure alters hippocampal slice electrophysiology

Pregnant Sprague-Dawley rats consumed an ethanol-containing liquid diet containing 0%, 17.5% or 35% ethanol-derived calories (EDC) from gestation day 8 until parturition. A fourth group was fed standard rat chow as an ad lib diet control. Animals prenatally exposed to ethanol had lower birth weights and impaired passive avoidance learning at 17 days of age. At 90 days of age synaptic potentials in area CA1 were characterized electrophysiologically in hippocampal slices. Slices from ethanol-exposed rats had significantly greater paired-pulse facilitation compared to 0% EDC and ad lib controls. Histological examination of brains from litter mates did not indicate altered number, density or nuclear volumes for neurons in area CA1. These data indicate that prenatal ethanol exposure can result in abnormal hippocampal synaptic physiology and suggest that these changes may contribute to the learning impairments observed in rats following such exposure.