Aims: The study used an animal model of fetal alcohol spectrum disorders (FASD) to investigate the impact of alcohol exposure during a period equivalent to all three trimesters in humans on social recognition memory. It was hypothesized that the effects on specific aspects of social recognition memory would be sexually dimorphic.
Methods: This study exposed rats to ethanol during both the prenatal and early postnatal periods. Two control groups included a group exposed to the administration procedures but not ethanol and a non-treated group. At approximately 90 days, all rats were tested repeatedly in a test of social recognition memory with a juvenile animal of the same sex. Experimental rats of both sexes were allowed to investigate an unknown juvenile for either 2, 3 or 5 min and then, after a delay of 30, 60, 120 and 180 min, were allowed to investigate the same juvenile for 5 min.
Results: Male rats investigated the juvenile for much longer than female rats. Ethanol-exposed male rats showed a deficit in recognition memory that was evident with longer delays when the initial investigation time was either 2- or 3-min long. In contrast, ethanol-exposed female rats showed a deficit in recognition memory only when the initial investigation period was of 2 min. Measurement of oxytocin receptor binding in the amygdala region indicated that ethanol exposure lowered oxytocin receptor binding in females but not males.
Conclusions: The results suggest that ethanol exposure during development caused a deficit in memory duration but not encoding in males and a deficit in encoding but not memory duration in females. The deficit in ethanol-exposed females may be related to changes in oxytocin receptors in the amygdala.