Reversal of a postnatal alcohol-induced deficit in learned persistence in the rat by d-amphetamine.
Periodic (high peak) exposure to alcohol during early infancy in the rat has been shown to disrupt the partial reinforcement extinction effect (PREE), a measure of persistence learning, when rats were tested at weaning age. The current study examined the effects of d-amphetamine (0.3 mg/kg, i.p.) on the PREE after early postnatal exposure to alcohol (4.5 mg/kg) delivered in a milk-based diet or an isocaloric control diet via oral intubation once a day on postnatal days 4 to 9. On postnatal days 20 and 21, rats were trained on either a continuously reinforced or partially reinforced schedule of food reward, followed by extinction. Rats were randomly assigned to eight conditions, depending on diet, drug, and reward schedule. The results were (1) a replication of the finding that periodic (high peak) exposure to alcohol diminishes the PREE, and (2) that amphetamine restores the PREE to normal levels in alcohol-treated animals, and may reduce the PREE in control subjects. The possible role of noradrenergic and dopaminergic systems in situations of extinction and nonreward are discussed.