Perinatal responsiveness to alcohol's chemosensory cues as a function of prenatal alcohol administration during gestational days 17-20 in the rat

Rat fetuses proximal to birth process alcohol-derived cues when the drug is directly delivered into the amniotic fluid. Prior evidence indicates that chemosensory sensation is detected during gestational Day 17 (GD17). In the present study Wistar-derived pregnant females received 0, 1, or 2 g/kg/day of alcohol (intragastric intubation) during GDs 17-20. Prenatal treatment failed to affect different maternal-fetal and perinatal physical parameters, e.g., placenta weight, umbilical cord length, offspring's body weights, weights and/or size of the olfactory bulbs, cerebral hemispheres, and cerebellum. Alcohol chemosensory responsiveness assessed in a perinatal motor activity test, indicated that pups pretreated with the 1 and 2 g/kg alcohol dose exhibit significant decrements in their activity rate when alcohol odor is presented in the test chamber. Alcohol concentrations in maternal and fetal blood and in the amniotic fluid were also recorded through head-space chromatography 1 h after females received the last intubation procedure (GD20) with the 1 or 2 g/kg alcohol doses. Dose-dependent alcohol concentrations across the different sites of assessment were recorded. As indicated by previous studies, even the alcohol level in the amniotic fluid attained with the 1 g/kg alcohol dose is above threshold values in terms of allowing fetal chemosensory stimulation with alcohol-derived cues. The results suggest that maternal ethanol intoxication during the last days of pregnancy leads to fetal exposure to alcohol's sensory attributes and that this experience subsequently modifies responsiveness to these cues. (C) 1996 Academic Press, Inc.