Fetal alcohol exposure produces delay-dependent memory deficits in juvenile and adult rats

The effects of prenatal alcohol exposure on both behavioral and neurobiological measures may be dependent, in part, on the age of the animal. Previous evidence from our laboratory has shown a delay-dependent memory deficit in young adult fetal alcohol exposure (FAE) rats. The present study examined the effects of FAE on an alternation task at three different ages of male rats: juvenile (days 38 to 44), young adult (days 82 to 89), and adult (days 173 to 180). In the present study, subjects were three age groups of male offspring of Sprague-Dawley rats fed 35% ethanol-derived calories, pair-fed with sucrose, or control-fed with lab chow during the last week of gestation. Subjects were food-deprived before training and then trained in the T-maze for food reward. Rats were trained to alternate at no delay on six sessions over 3 days. On each of the next 4 days, rats were tested for two sessions at delays of 10 sec, 30 sec, 60 sec, and then a no-delay condition. On the final day of testing, rats were tested at the 60-sec delay for 10 trials. No FAE effect was observed at the short delay during the training sessions; however, the adult group had a lower performance on the training sessions, compared with the other groups. In the test session, the FAE groups showed a delay-dependent memory deficit. FAE rats in all three age groups were impaired at the 30-sec and 60-sec delays, compared with their control groups. However, only the juvenile FAE rats were impaired at the 10-sec delay, compared with the control groups. The FAE groups were not impaired when tested again at no delay. These findings indicate long-term consequences of prenatal alcohol exposure in rats on memory retention that is present up to 6 months of age. In addition, the finding that only the juvenile FAE rats showed impairment at the 10-sec delay indicates that certain deficits may decrease as the FAE rat matures.