The role of stress and age in spatial navigation deficits following prenatal exposure to ethanol

Abstract

The effects of prior experience with swimming on performance in a Morris water task were examined in 21- and 24-day-old rats whose dams consumed liquid diets containing either 35% or 0% ethanol-derived calories (EDO on Days 6-20 of pregnancy, or ad-lib lab chow and water (LC) throughout pregnancy. At 21 days of age, prenatal alcohol-exposed (35%EDC) rats displayed impaired performance relative to pair-fed (0%EDC) and chow-fed (LC) control groups, regardless of prior swimming experience. At 24 days of age, the performance of 35%EDC rats not given swimming experience prior to training did not differ from controls, which suggests that some recovery from fetal alcohol effects had occurred. Among groups given prior swimming experience, however, the 35%EDC rats took longer than the 0%EDC or the LC control groups to find the platform in the Morris maze at 24 days of age. The results suggest that in utero ethanol exposure produces a transient deficit in spatial navigation abilities at around 21 days of age, but that animals appear to recover by around 24 days of age. This deficit appeared to be revealed in 24-day-old rats by giving the animals swim experience prior to training. The results suggest that the present and similar deficits and in spatial navigation in prenatal alcohol-exposed rats may be due to increased and/or prolonged stress responses to the task in alcohol-exposed offspring, and not to a hippocampus-mediated deficit in spatial navigation per se.