Fetal associative learning mediated through maternal alcohol intoxication

Background: The aim of the present study was to analyze whether alcohol as an unconditioned stimulus is capable of supporting associative learning in near-term fetuses. Methods: In experiment 1, we determined pharmacokinetic profiles of alcohol and of an aromatic substance (cineole) in amniotic fluid and maternal bloo d during late gestation. The results obtained through gas chromatographic a nalysis allowed a second experiment in which we explicitly paired peak leve ls of cineole with peak levels of alcohol in amniotic fluid and blood, by i ntragastrically administering cineole and ethanol to the dams during gestat ional days 17 through 20 (paired condition). Control groups were dams given cineole 4 hr before commencement of an acute state of alcohol intoxication (long-delay group) or were only exposed to water administrations (water co ntrol group). The progeny were evaluated during postnatal day 16 in terms o f behavioral responsiveness to intraorally infused solutions (cineole or al cohol presented in milk vehicle, or milk alone). Results: Mouthing responsiveness to cineole was strongly affected by the na ture of prenatal treatments. Pups in the paired prenatal condition mouthed significantly less than did long-delay and water controls. Physical and beh avioral measures allowed us to reject the possibility that these effects we re due to teratogenic effects of alcohol during late gestation. Conclusions: These results indicate that before birth, rat fetuses are capa ble of acquiring associative memories supported by the unconditioned proper ties of alcohol. This associative memory can be expressed during infancy th rough a significant reduction in mouth movements in the presence of the spe cific orosensory cue explicitly paired with alcohol interoceptive effects i n utero.