Prenatal ethanol exposure and hyperactivity in rats: effects of d-amphetamine and alpha-methyl-p-tyrosine.

Pregnant Wistar rats were exposed to either a liquid diet containing ethanol, pair-fed an identical diet with sucrose substituted for ethanol, or received ad lib chow and water, during days 6-19 of gestation. The activity of their offspring was tested at 10, 16, 22 or 28 days of age. Pups exposed to alcohol prenatally were more active than controls at 16 and 22 days of age. Thirty min after being placed in the activity chamber, the pups were injected with either 0, 0.5, 1.0 or 4.0 mg/kg of d-amphetamine sulphate, and returned to the chamber for a further 120 min. Amphetamine brought about a dose-related increase in activity at 10, 22 and 28 days. At 16 days, peak activity was associated with the 0.5 mg/kg dose, activity declining at the higher doses. In a second study, pups received injections of 0, 25, 50 or 100 mg/kg of alpha-methyl-p-tyrosine (AMPT). Activity was unaffected by AMPT at 10, 22 or 28 days of age, but was increased at 16 days of age by the 25 and 50 mg/kg doses. Importantly, the time courses of the effects on activity of both d-amphetamine and AMPT were the same regardless of the treatment received during gestation. These data indicate that the hyperactivity associated with fetal alcohol exposure is not a result of alterations in the ontogeny of the catecholamine systems involved in arousal.